And next, we turn, tonight, to the tension rising around the world, as Russian president Vladimir Putin casts his shadow across the boundary of Europe and Russia. Tonight, his troops are holding firm in a corner of Ukraine known as crimea. So, will he push any further? And has the U.S. And its allies decided to push back? First, ABC's chief foreign correspondent, terry Moran, on the front lines of the crisis in Ukraine. Reporter: Vladimir Putin, proudly watching Russian military exercises today. But his eye was on his troops a thousand miles south, here on the crimean peninsula in Ukraine. His air force controls the skies. His army controls the roads, borders and military bases. And his Navy controls the ports and seas surrounding this peninsula. Putin rules in crimea now. And here is why he did it. Look at Ukraine and crimea, down in the south there, jutting out into the waters of the black sea, home to a critical port the Russian Navy has used for centuries. So, Putin claiming he is defending ethnic Russians in crimea, has seized the entire peninsula. Russia is on the wrong side of history on this. We are examining a whole series of steps, economic, diplomatic, that will isolate Russia. Reporter: The fear tonight, that the Ukrainian military or people will try to stop him, toiching off a bloody war. That's why secretary of state Kerry is racing to the region, making sure they hold their fire. Because the Russian military would likely crush any Ukrainian forces. It's a generation behind on the terms of advancement of technology. Reporter: Russia has 845,000 uniformed troops. Ukraine, just 130,000. They are spread throughout the country. And some are pro-russian, who may defect. And Russia's got twice as many tanks, six-times as many aircraft, ten-times as many ships. Ukrainian troops in crimea, remain bottled up in their bases by Russian soldiers. As we saw at the feodosia base, by fiercely pro-russian crowds. They stopped us from talking to Marines inside the base. And they angrily forced us to turn back, providing a jeering escogscort all the way. Everyone is on-edge here. No one knows what tomorrow may bring, except, perhaps, Vladimir Putin. Terry Moran, ABC news, Ukraine. Thank you, terry. And the uncertainty of Ukraine

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